Abstract
In this technologically advancing world, the demand for more energy, oil and gas production is rapidly escalating. To accomplish this, people have inclined more towards completely floating offshore structures, deployed in deep waters. A semi-submersible is selected in the present study, due to its better response characteristics and stability under harsh environmental conditions. The semi-submersible is position restrain with spread mooring lines incorporated with submerged buoy at different locations has been studied. A detailed numerical analysis is carried out using Ansys Aqwa for dynamic response analysis of semi-submersible under the combination of wind, wave, and current forces for 0°, 45°, and 90° directions. It was observed that damping ratios and natural periods had been affected based on the position and number of submerged buoys in the mooring system. Also, reduction in mooring force after incorporating buoy in the mooring lines was observed. Subsequently, a Matlab code based on the S-N curve approach was generated and employed to investigate the fatigue damage of mooring lines under dynamic variation of mooring forces. When pegged with submerged buoys, fatigue life of mooring lines is increased under intact and postulated damaged mooring conditions. Moreover, coupling of motion responses of semi-submersible is observed, and unbounded response is not seen in any degrees-of-freedom, even during damaged condition of mooring lines.
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The authors thank PG Senapathy Centre, Indian Institute of Technology Madras for providing computational facility required for the present work.
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Article Highlights
• Dynamic response analysis of a semi-submersible under wind, wave and current loads for various directions under intact and damaged mooring conditions has been carried out.
• A chain-wire-chain mooring system is pegged with buoys at all the possible locations for restraining the motions of the semi-submersible.
• Investigation of fatigue life of mooring lines under intact and postulated damaged conditions has been done.
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Uddin, S.A., Tousif, M. Dynamic Analysis of a Symmetrically Moored Semisubmersible Under Various Possible Mooring Combinations. J. Marine. Sci. Appl. 23, 160–181 (2024). https://doi.org/10.1007/s11804-024-00390-w
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DOI: https://doi.org/10.1007/s11804-024-00390-w